Energy and Energy Transfer

How the earth captures the sun’s energy and uses it to “do work”

What is energy?

– ability to do work

Cars need energy to move

Animals need energy to grow, move, make noise, etc

Types of energy

• Mechanical energy– Move cilia, flagella, cytoskeleton, muscles

• Transport energy– Active transport – pumping ions and

molecules across a membrane against the gradient

• Chemical energy (like ATP)– Stored in bonds. Can be used to start

reactions that may not start spontaneously

Where do cars get energy?

– from burning fuel

–Specifically oil and gasoline

Chemical Energy is stored in fuels

- Burning oil and gasoline release energy in the form of heat and light ; The energy also allows the car to move.

- Gasoline is organic (C and H). When gasoline reacts with oxygen you get a combustion reaction. The products of ALL combustion reactions are carbon dioxide (CO2) and Water (H20)

What is our fuel? - Food!

- Specifically Glucose (simple carb)

- We disassemble glucose and put theenergy from the bonds into ATP

Creating ATP

But where does the energy stored in glucose in our food come from?

THE SUN!!!

Really? How?• Let go through step by step.

1. Where did your glucose come from?

2. How did the glucose get in the food?

3.How did she get the glucose?

4. How did the glucose get in the grass?

5. Where did the energy to make the glucose come from?

SO, long story short,

- the chloroplasts take energy from the sun and put it into a glucose molecule (Photosynthesis)

- through the food chain, glucose gets passed from organism to organism

- eventually mitochondria of some organism takes the energy back out, by breaking down the glucose (Cell respiration)

Types of Batteries

• Adenosine Triphosphate: ATP– cycles between ATP (high energy)

and ADP (low energy) by adding or removing a phosphate

Types of Batteries• Electron Carriers: cycle between low

energy “empty” form and high energy “full” form by adding or removing electrons.

–We can “empty” these electron carriers to charge ATP

Types of Batteries

–There are three different electron carriers: NADPH; NADH and FADH2

Let’s start by getting the energy from the sun into the glucose molecule

Photosynthesis

Key terms:

• Heterotrophs: Organisms that get food from somewhere else–Examples??

• Autotrophs: organisms that make food for themselves–Photoautotrophs use light energy to

make their food• Examples?

–Chemoautotrophs use the energy in inorganic compounds to make their food• Examples?

• Understanding a little about light is important! Refer to your “Science of light and Color” assignment to help!

Electromagnetic Spectrum

Where does photosynthesis happen

• http://dendro.cnre.vt.edu/forestbiology/photosynthesis.swf

• Not all cells in a plant photosynthesize. Let’s take a moment to identify WHERE we would find chloroplasts

Photoautotrophs undergo Photosynthesis

• So what organelle is in their cells?

Granum (plural Grana)

Thylakoid

Stroma

What makes it Green?

• Pigment called Chlorophyll (There are two chlorophylls)

• A pigment is a substance that absorbs light

What color light bounces off chlorophyll?

GREEN!!!

• Carotenes and xanthophylls*: other plant pigments (orange and yellow) that absorb different wavelengths of sunlight than the chlorophylls do.

• When can we see these??

* ZAN-tho-fills

FALL!!!

Overall SUMMARY Reaction• Photosynthesis requires MANY reactions but we can

summarize it with the following reaction

What other molecules participate in the reaction?

Why is energy shown “not in the reaction”?

6CO2 + 6H2O + 6O2

(Glucose)

C6H12O6

Getting CO2 and Water into the leaf

Stomata (plural)

Root Hairs

How does energy get into the leaf?

Some light is transmitted (passes through) as well.

What colors are reflected?

Absorbed?

The peaks are wavelengths that are ABSORBED by the leaf.

What colors are absorbed?

What type of cells absorb light energy?

MESOPHYLL

CELLS

contain

chloroplasts

• Two Phases of PhotosynthesisLight reactions: need light;

- uses light energy to “charge” two energy molecules: ATP and NADPH

- proteins needed for the reaction are embedded in the thylakoid membrane

- Uses: 6H2O produces: 6O2

How does this work?

• http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

• What component of water travels along the membrane and is utilized to form NADPH?

• What component of water travels back and forth THROUGH the membrane and is utilized to form ATP?

YOU NEED TO KNOW THE ANSWERS TO THESE TWO QUESTIONS!

• Two Phases of PhotosynthesisCalvin cycle: doesn’t need light;

- Uses the ATP and NADPH “charged” by the light reactions (carry energy) to link CO2 together to build C6H12O6

- Enzymes for the Calvin cycle are found in the stroma

Reactant: 6CO2 Product: C6H12O6

Putting it Together

The poetry of photosynthesis

• http://www.pbs.org/wgbh/nova/nature/photosynthesis.html

What wavelengths oflight are absorbed?

Which pigments?

Thylakoid membranePhotosystems:groups of pigmentsLight splits water (H+ and e-)Proton gradient ATPNADP carries electrons

ATP andNADPHend up instroma

Water starts insidethe thylakoids

Glucose will do one of two things:

1. Move to the mitochondria to be converted into ATP through Cell respiration

2. Go through dehydration synthesis to build a big starch chain and be stored for future use

Follow the Energy

• Where did the energy start?

• Where did it go next?

• Where is it at the end of photosynthesis?

Factors that affect Photosynthesis

• Light intensity (how bright/strong)

• Wavelength (color of light)• Temperature: 0 – 35 degrees C

• Water

• CO2 levels

Why do each of these affect photosynthesis?

Why Mistletoe at Christmas?• Druids (100 AD) thought that

Mistletoe could help cure diseases and protect people from witches. They even thought it could help people and animals have more babies. So the Druids had a special ceremony that would happen in late December or early January. Priests would cut mistletoe out of oak trees and then give the mistletoe to people to hang in their houses so that it would ward off evil spirits.

Why kissing?

• The Vikings! (800 BCE) had a lot of gods (like the Greeks did). One of their gods -- Balder -- was killed with a poison made from mistletoe. His mother -- Frigga -- was able to bring him back to life after three days by reversing the effects of the poison. Once she did that, she kissed everyone who walked under mistletoe because she was so happy to get her son back.

EXCEPTIONS

• Some protists are heterotrophic and photosynthetic

• Some plants are heterotrophic and photosynthetic

• Some plants are parasitic and photosynthetic.

Exceptions to the Rules:

• Autotrophic Bacteria:

–Example: Cyanobacteria (“Blue” bacteria)

Exceptions to the Rules:

• Autotrophic Protists:

–Example: Volvox and Euglena

Exceptions to the Rules:• Heterotrophic plants: some plants can

get some food from other organisms

– EXAMPLE: Mistletoe: makes food (PS) AND takes sap (high in sugar) from other trees

Hemi - parasite

Exceptions to the Rules:

Venus Flytrap: traps and digests insects as a food source

Exceptions to the Rules:

Dodder plant: roots grow into other plants and steals water and glucose

How do we get the energy back out?

Cell Respiration – a series of chemical reactions that extract energy from glucose to “charge” ADP to make ATP.

Starts in the cytoplasm and ends in the mitochondria.

How do we get the energy back out?

Overall reaction

+ 6O2 6CO2 + 6H2OC6H12O6

ATP

Two types of Cellular Respiration

Anaerobic: no free oxygen required

- performed by most bacteria

- Also by yeast and animal cells when lacking O2

- two steps: Glycolysis, fermentation

- makes 2 ATP per glucose

Two types of Cellular Respiration• Aerobic: requires FREE oxygen, O2 gas to get

ATP from glucose

– three steps: glycolysis, krebs, electron transport chain

– performed by plants, animals, yeast, protists, fungus.

– Generates 36 ATP per glucose

Anaerobic step 1: Glycolysis• Occurs in cytoplasm

• Summary: split glucose in half to charge a few ATP and NADH

• Reaction: Glucose 2 pyruvate

• Energy molecules used: 2ATP

• Energy molecules made: 4ATP and 2NADH

Fermentation• Occurs in cytoplasm• Summary: “empty” the NADH so we can

repeat glycolysis with the next glucose

–2Pyruvate CO2 and Ethanol (yeast)

or

- 2Pyruvate Lactic Acid (bacteria and muscle cells)• NO MORE ATP CHARGED!

ATP Tallies:

Anaerobic:

- Glycolysis: used 2, made 4

- Fermentation: used 0, made 0

Total: +2 per glucose

Aerobic step 1: Glycolysis

• SAME AS STEP 1 OF ANAEROBIC!

Krebs• Occurs in mitochondria

• Summary: break down pyruvate into CO2; use energy in pyruvate to charge ATP, NADH and FADH2

KrebsReaction:

–2Pyruvate 2Acetyl-CoA + 2CO2

–2Acetyl-CoA 4CO2

–Energy molecules made: 2ATP + 2FADH + 8NADH

–Can bacteria do Krebs??

Electron Transport Chain• Occurs in mitochondria

• Summary: Gather up ALL the electron carriers and “empty” them to “charge” lots of ATP

Electron Transport Chain• Reaction:

–O2 H2O

Energy molecules USED: 10 NADH (from krebs and glycolysis) + 2 FADH (from krebs)

Energy molecules MADE: 32 ATP

ATP Tallies:

Aerobic: - Glycolysis: used 2, made 4 - Krebs: used 0, made 2 - ETC: used 0, made 32Total: +36 ATP per glucose

Overall Energy Summary for Aerobic Respiration

Glucose + 2ATP 2 Pyruvate + 4ATP + 2NADH

Reactants (used up/broken down) Products (created/built up)

2 Pyruvate 2CO2 + 2Acetyl-CoA + 2NADH

2Acetyl-CoA 6NADH + 2FADH2 + 2ATP+ 4CO2

10NADH + 2FADH2 + 6O2 32ATP + 6CO2 + 6H2O

What’s Left?

Final Reaction for Aerobic Respiration

Putting it together:

Chloroplast

Sun

Mitochondria

C6H12O6 + O2CO2 + H2O

36ATP